The present invention relates to a unit for transferring articles.
More specifically, the present invention relates to a unit for transferring groups of cigarettes on a cigarette packaging machine, to which the following description refers purely by way of example.
Cigarette packaging machines provide for forming groups of normally twenty cigarettes, and for packaging the groups in packaging material. In one packaging machine, the cigarettes are housed in bulk inside a hopper having a number of substantially vertical outlets, down which the cigarettes are fed by force of gravity on to a plate on which a group of cigarettes is formed.
The machine comprises a transfer unit having a pocket conveyor for feeding the groups in a given first direction; a pusher for each outlet, to expel the groups of cigarettes from the hopper outlet in a second direction perpendicular to the first direction; and, for each outlet, a guide located between the outlet and the conveyor and aligned with the hopper outlet to guide the groups of cigarettes into a conveyor pocket along a path parallel to the second direction.
The conveyor cyclically arrests a pocket at each guide, and, while the pockets are stationary, the pushers transfer respective groups of cigarettes through the respective guides from the outlets to the pockets. Once the groups are transferred from the outlets to the respective pockets, the pockets are fed forward in the first direction to transfer the groups to packaging wheels on the machine to wrap the groups in respective sheets of packaging material to form packets of cigarettes.
When any one of the pushers, for any reason, fails to complete its travel, so that the group of cigarettes is located partly inside the pocket and partly inside the guide, the forward movement of the pocket in the first direction subjects the group to shearing stress, which is opposed strongly by the group of cigarettes, on account of the guide having compressed the cigarettes together, so that the group acts substantially as a single body and is resistant enough to cause failure of the weaker or less firmly connected structural elements. In the case in question, the worst damage is caused to the pocket, which breaks away from the conveyor.
The above drawback is further compounded by the pocket having to be fitted back on to the conveyor, which means arresting the whole unit, and consequently the machine as a whole, for relatively long periods.
It is an object of the present invention to provide a unit for transferring articles, designed to eliminate the above drawback of known transfer units, and which in particular need not be arrested in the event of incomplete transfer of the article.
According to the present invention, there is provided a unit for transferring articles, in particular groups of cigarettes; the unit comprising a conveyor having at least one pocket for housing the articles and for feeding the articles in a first direction; and a guide for guiding the articles into a said pocket along a transfer path in a second direction crosswise to said first direction; and the unit being characterized by comprising a safety device comprising a guide member adjacent to the conveyor and movable between a work position defining part of the transfer path, and an emergency position remote from the transfer path; and a first actuator for setting the guide member to the emergency position when the articles transmit to the guide member a force over and above a threshold value.